This application claims priority under 35 USC xc2xa7 119 to French Patent Application No. 0209153 filed on Jul. 18, 2002.
The invention relates to a method of making a composite insulator for medium voltage distribution, the insulator comprising a rod surrounded by an insulating coating and provided at its two ends with two metal end fittings, respectively.
A composite insulator of this type is described, for example, in French patent application No. 2 514 546. That patent application teaches making the connection between the rod and a metal end fitting of the insulator by using a ductile tube, assembly being performed by sleeve coupling.
The object of the invention is to provide a method of manufacturing such an insulator at lower cost by standardizing the manufacture of the insulator body.
The method of the invention consists in the following steps:
fixing two respective metal interfaces (3; 13) to the two ends of the rod, the metal end fittings of the insulator subsequently being fixed to the interfaces; and
putting the coating into place around the rod and around the metal interfaces while leaving an end portion of each metal interface uncovered by the coating so as to enable the metal end fittings to be fixed thereto subsequently.
With this method, it is possible to mass produce standard insulator bodies having the same dimensions without their end fittings, which end fittings can be put into place subsequently immediately prior to delivering the insulators to the customer or the worksite. The fact that the end fittings are not fixed to the composite insulator body while the insulating coating is being put into place means that a larger number of insulator bodies can be put into the same mold for putting the coating into place, thereby enabling economies of scale to be achieved and reducing the unit price of manufacturing an insulator.
The invention extends to the following features of the method and to an insulator made by the method:
the coating is put into place by injection molding;
each metal interface is fixed to an end of the rod by a swaging technique;
each metal end fitting is fixed to a metal interface by a swaging technique with the help of a worksite press;
each metal interface is a tube;
the tube has an internal transverse wall providing a sealed separation between the rod and a metal end fitting;
the internal wall is a metal web; and
the internal wall is a separate fitting.